Idiopathic Hypogonadotropic Hypogonadism Research Articles

Clinical feature and genetic analysis of a patient with Idiopathic hypogonadotropic hypogonadism due to a novel variant of CHD7 gene

To explore the clinical feature and genetic etiology of a patient with normosmic idiopathic hypogonadotropic hypogonadism (nIHH) due to variant of CHD7 gene. A patient who had presented at Anhui Provincial Children's Hospital in October 2022 was selected as the study subject. Clinical data of the patient was collected. The patient and his parents were subjected to trio-whole exome sequencing. Candidate variant was verified by Sanger sequencing and bioinformatic analysis. The patient had featured delayed development of secondary sexual characteristics but normal olfactory function. Genetic testing revealed that he has harbored a c.3052C>T (p.Pro1018Ser) missense variant of the CHD7 gene, for which both of his parents were of the wild type. The variant has not been recorded in the PubMed and HGMD databases. Analysis of amino acid sequences suggested that the variant site is highly conserved, and the variant may affect the stability of protein structure. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.3032C>T variant was classified as a likely pathogenic (PS2+PM2_Supporting+PP2+PP3+PP4). The delayed development of secondary sexual characteristics of the patient may be attributed to the c.3052C>T (p.Pro1018Ser) variant of the CHD7 gene. Above finding has expanded the variation spectrum of the CHD7 gene.

Congenital hypogonadotrophic hypogonadism, induction of minipuberty, and future fertility.

A 33-year-old man with Kallmann syndrome had received pulsatile GnRH as an infant for the treatment of cryptorchidism. As an adult, his treatment for fertility with gonadotrophins was unusually rapid compared with expectations, with a total sperm count of 25 million after only 12 months of gonadotrophin therapy. We propose that pulsatile GnRH treatment as an infant induced minipuberty and facilitated his successful, rapid response to therapy. We also propose that identification of the absence of minipuberty in infants with clinical signs suggesting congenital hypogonadotrophic hypogonadism (CHH) is an opportunity for intervention with pulsatile GnRH yielding benefits for fertility decades later. Absence of minipuberty in males with CHH results in low Sertoli cell numbers and delayed response to induction of spermatogenesis in adulthood. Presentation with 'red flags' for androgen deficiency including cryptorchidism at birth, with or without micropenis, should prompt screening for CHH and minipuberty by measurement of gonadotrophins and testosterone in the first 2 months after birth. Pulsatile GnRH therapy in patients with CHH, given prior to age of attainment of Sertoli cell maturation, can replicate the normal physiology of minipuberty, thereby priming the testis for future fertility.

Retard pubertaire d’origine nutritionnelle : Analyse d’une série de cas d’un centre univer sitaire de l’Est Algérien.

Introduction. Malnutrition is one of main reasons for growth and puberty delay. Objective. To determine the prevalence of functional hypogonadotropic hypogonadism (FHH) from nutritional origin, and to study its clinical and biological characteristics. Population and methods. This retrospective study was conducted on 32 cases of FHH [secondary to Chronic Diseases + Constitutional Delay of Growth and Puberty (CDGP)], from a series of 125 patients evaluated for delayed puberty (DP) in the Endocrinology Department of the University Hospital Center of Constantine, between 2000 and 2010, and follow-up for at least 5 years. The diagnosis of malnutrition was clinical, according to the American Academy of Nutrition and Dietetics consensus. Each patient received a general check-up and a gonadotropic and thyrotropic hormonal assay. Other etiological explorations were clinically guided. FHH group was compared with isolated hypogonadotropic hypogonadism (IHH) group. Results. FHH constituted 26% of the series [21 boys/11 girls, (p<0.5)] vs 24% of IHH group. Secondary HHF represented 20% of cases in the series against 6% of CDGP. Malnutrition represented 27% of the series, 11% of which were directly responsible for delayed puberty (DP). Protein-energy undernutrition and iron deficiency anemia, due to inadequate intake, accounted for 62% of nutritional causes. There was a break in the growth curve in 97% of FHH vs 26% of IHH patients (p<0.001). FHH tripled the risk for developing growth retardation. Testicular volume of FHH group was 2.82±0.73 mL (2.69±0.4 mL in patients with malnutrition) vs 2.09±0.87 mL for IHH group (p<0.05). Conclusion. Despite therapeutic progress, DP in CD is common, representing a severity indicator, and poor control of CD. Prevention of FHH requires early detection, nutritional supplementation, and good control disease.

Prevalence of Deleterious Variants in MC3R in Patients With Constitutional Delay of Growth and Puberty.

The melanocortin 3 receptor (MC3R) has recently emerged as a critical regulator of pubertal timing, linear growth, and the acquisition of lean mass in humans and mice. In population-based studies, heterozygous carriers of deleterious variants in MC3R report a later onset of puberty than noncarriers. However, the frequency of such variants in patients who present with clinical disorders of pubertal development is currently unknown. This work aimed to determine whether deleterious MC3R variants are more frequently found in patients clinically presenting with constitutional delay of growth and puberty (CDGP) or normosmic idiopathic hypogonadotropic hypogonadism (nIHH). We examined the sequence of MC3R in 362 adolescents with a clinical diagnosis of CDGP and 657 patients with nIHH, experimentally characterized the signaling properties of all nonsynonymous variants found and compared their frequency to that in 5774 controls from a population-based cohort. Additionally, we established the relative frequency of predicted deleterious variants in individuals with self-reported delayed vs normally timed menarche/voice-breaking in the UK Biobank cohort. MC3R loss-of-function variants were infrequent but overrepresented in patients with CDGP (8/362 [2.2%]; OR = 4.17; P = .001). There was no strong evidence of overrepresentation in patients with nIHH (4/657 [0.6%]; OR = 1.15; P = .779). In 246 328 women from the UK Biobank, predicted deleterious variants were more frequently found in those self-reporting delayed (aged ≥16 years) vs normal age at menarche (OR = 1.66; P = 3.90E-07). We have found evidence that functionally damaging variants in MC3R are overrepresented in individuals with CDGP but are not a common cause of this phenotype.

AXL/Gas6 signaling mechanisms in the hypothalamic-pituitary-gonadal axis.

AXL is a receptor tyrosine kinase commonly associated with a variety of human cancers. Along with its ligand Gas6 (growth arrest-specific protein 6), AXL is emerging as an important regulator of neuroendocrine development and function. AXL signaling in response to Gas6 binding impacts neuroendocrine structure and function at the level of the brain, pituitary, and gonads. During development, AXL has been identified as an upstream inhibitor of gonadotropin receptor hormone (GnRH) production and also plays a key role in the migration of GnRH neurons from the olfactory placode to the forebrain. AXL is implicated in reproductive diseases including some forms of idiopathic hypogonadotropic hypogonadism and evidence suggests that AXL is required for normal spermatogenesis. Here, we highlight research describing AXL/Gas6 signaling mechanisms with a focus on the molecular pathways related to neuroendocrine function in health and disease. In doing so, we aim to present a concise account of known AXL/Gas6 signaling mechanisms to identify current knowledge gaps and inspire future research.

Assessing hypothalamic pituitary gonadal function in reproductive disorders.

Reproductive conditions secondary to disorders of the hypothalamic-pituitary-gonadal (HPG) axis are common and are associated with important health implications and considerable psychosocial impact. Basal and dynamic tests enable interrogation of individual components of the HPG axis, facilitating diagnosis and understanding of the pathophysiology of reproductive disorders. Onset of puberty is controlled by hypothalamic gonadotrophin-releasing hormone (GnRH) neuronal function. To date, a dynamic test of hypothalamic function is not yet available. Therefore, accurate differentiation of pubertal disorders such as constitutional delay of growth and puberty (CDGP) and congenital hypogonadotrophic hypogonadism (CHH) as causes of delayed puberty is challenging due to similar clinical presentations and hormonal profiles. Likewise, although the two commonest reproductive disorders in women, polycystic ovary syndrome (PCOS) and functional hypothalamic amenorrhoea (FHA) have disparate hypothalamic function, oligo/amenorrhoea frequently poses a diagnostic conundrum owing to the overlap in the criteria used to define both conditions. This review aims to describe pubertal and reproductive disorders secondary to pathologies affecting the HPG axis. Challenges encountered in clinical practice in differentiating pubertal and reproductive conditions are reviewed in conjunction with the utility of baseline and dynamic endocrine tests to interrogate specific components of the HPG axis. We also highlight putative hypothalamic, pituitary, and gonadal markers in development that could improve the diagnosis of patients presenting with disorders of puberty or reproduction.

Vigorously promote the research on diagnosis, treatment and genetic counseling of children with congenital hypogonadotropic hypogonadism

先天性低促性腺激素性性腺功能减退症（CHH）是罕见的影响青春期发育和成年期生育的疾病。述评通过儿童期开展CHH诊治的意义、面临的困难、遗传学研究助力儿童CHH诊断及未来的研究方向4个方面呼吁从事儿童性腺疾病诊疗的医师进行更多和深入的大型临床研究以获得更多证据，为减少性腺疾病对患儿心理、骨代谢及成年期心血管风险等的影响，为成年期生育力提升提供更多保障，为家庭避免再发生此类疾病提供背景知识。.

Expert consensus on genetic counseling and reproductive related recommendations for congenital hypogonadotropic hypogonadism

先天性低促性腺激素性性腺功能减退症（CHH）是一类罕见的影响青春期发育和成年期生育的遗传性疾病，根据是否合并嗅觉异常分为嗅觉异常的卡尔曼综合征和嗅觉正常的CHH。超过50个基因参与CHH发病，遗传模式包括X连锁隐性、常染色体隐性和常染色体显性遗传，至少20%呈寡基因遗传。该类患者及其家庭的遗传咨询成为疾病诊疗中不可或缺的重要部分。.

Clinical Characteristics and Genetic Analyses of Patients with Idiopathic Hypogonadotropic Hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) is classified into two groups-Kalman syndrome and normosmic IHH (nIHH). Half of all cases can be explained by mutations in >50 genes. Targeted gene panel testing with nexrt generation sequencing (NGS) is required for patients without typical phenotypic findings. The aim was to determine the genetic etiologies of patients with IHH using NGS, including 54 IHH-associated genes, and to present protein homology modeling and protein stability analyzes of the detected variations. Clinical and demographic data of 16 patients (eight female), aged between 11.6-17.8 years, from different families were assessed. All patients were followed up for a diagnosis of nIHH, had normal cranial imaging, were without anterior pituitary hormone deficiency other than gonadotropins, had no sex chromosome anomaly, had no additional disease, and underwent genetic analysis with NGS between the years 2008-2021. Rare variants were classified according to the variant interpretation framework of the American College of Medical Genetics and Genomics (ACMG)/Association for Molecular Pathology. Changes in protein structure caused by variations were modeled using RoseTTAFold and changes in protein stability resulting from variation were analyzed. Half of the 16 had no detectable variation. Three (18.75%) had a homozygous (pathogenic) variant in the GNRHR gene, one (6.25%) had a compound heterozygous [likely pathogenic-variants of uncertain significance (VUS)] variant in PROK2 and four (25%) each had a heterozygous (VUS) variant in HESX1, FGF8, FLRT3 and DMXL2. Protein models showed that variants interpreted as VUS according to ACMG could account for the clinical IHH. The frequency of variation detection was similar to the literature. Modelling showed that the variant in five different genes, interpreted as VUS according to ACMG, could explain the clinical IHH.

Combined pituitary hormone deficiency harboring CHD7 gene missense mutation without CHARGE syndrome: a case report

BackgroundHeterozygous loss-of-function mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene cause CHARGE syndrome characterized by various congenital anomalies. A majority of patients with CHARGE syndrome present with congenital hypogonadotropic hypogonadism (HH), and combined pituitary hormone deficiency (CPHD) can also be present. Whereas CHD7 mutations have been identified in some patients with isolated HH without a diagnosis of CHARGE syndrome, it remains unclear whether CHD7 mutations can be identified in patients with CPHD who do not fulfill the criteria for CHARGE syndrome.Case presentationA 33-year-old woman was admitted to our hospital. She had primary amenorrhea and was at Tanner stage 2 for both pubic hair and breast development. She was diagnosed with CPHD (HH, growth hormone deficiency, and central hypothyroidism), and a heterozygous rare missense mutation (c.6745G > A, p.Asp2249Asn) in the CHD7 gene was identified. Our conservation analysis and numerous in silico analyses suggested that this mutation had pathogenic potential. She had mild intellectual disability, a minor feature of CHARGE syndrome, but did not fulfill the criteria for CHARGE syndrome.ConclusionsWe report a rare case of CPHD harboring CHD7 mutation without CHARGE syndrome. This case provides valuable insights into phenotypes caused by CHD7 mutations. CHD7 mutations can have a continuous phenotypic spectrum depending on the severity of hypopituitarism and CHARGE features. Therefore, we would like to propose a novel concept of CHD7-associated syndrome.

Successful pregnancy and delivery after ovulation induction therapy in a woman with congenital hypogonadotropic hypogonadism: a case report

BackgroundCongenital hypogonadotropic hypogonadism (CHH) is a rare disorder resulting from a deficient secretion of the episodic gonadotropin-releasing hormone, leading to delayed or absent puberty and infertility. In female patients with CHH, the most commonly used treatment is gonadotropin (Gn) therapy. Due to the rarity of the disease in females, there are limited case reports available. This article offers a management approach for this unusual disease that can be helpful for clinicians.Case presentationWe report the case of a 29-year-old woman who successfully achieved pregnancy and delivered healthy twin girls after ovulation induction therapy. The patient was diagnosed with CHH at 18 years of age due to primary amenorrhea and the absence of secondary sexual characteristics. After experiencing infertility for three years, the patient sought medical assistance for conceiving. The patient was treated with gonadotropin therapy due to anovulation. In her first treatment cycle, the initial dose of HMG used for treatment was 75IU, which was increased to 150IU after six days. However, the cycle was canceled due to follicular dysplasia. In the second cycle, the treatment began with an initial dose of 150IU, and the follicles grew normally, but the estrogen level was low. Consequently, the treatment was interrupted. In a third ovulation stimulation cycle, HMG was adjusted to 150IU, and recombinant LH was added. After 12 days of ovulation, three mature follicles grew, the estrogen level was normal,and the treatment resulted in successful ovulation and subsequent pregnancy. At 35 weeks of gestation, the patient underwent a cesarean section and delivered two healthy female infants weighing 2,405 g and 2,755 g with an Apgar score of 10/10.ConclusionsEarly diagnosis and timely and appropriate hormone replacement therapy are important for future pregnancy. Ovulation induction therapy is necessary to stimulate fertility. Gn therapy is a feasible and effective treatment for reproduction in CHH females, but the selection of Gn type and dosage must be personalized to maximize fertility outcomes. Effective treatment is available not only for inducing estrogenization and promoting fertility, but also for addressing concerns about psychological and emotional well-being.

Fertility induction in a man with congenital hypogonadotropic hypogonadism

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract #1405734: A Case of Male Idiopathic Hypogonadotropic Hypogonadism Presenting with Micropenis

Abstract #1405734: A Case of Male Idiopathic Hypogonadotropic Hypogonadism Presenting with Micropenis

The initiation and maintenance of gonadotropin-releasing hormone neuron identity in congenital hypogonadotropic hypogonadism.

Neurons that secrete gonadotropin-releasing hormone (GnRH) drive vertebrate reproduction. Genetic lesions that disrupt these neurons in humans lead to congenital hypogonadotropic hypogonadism (CHH) and reproductive failure. Studies on CHH have largely focused on the disruption of prenatal GnRH neuronal migration and postnatal GnRH secretory activity. However, recent evidence suggests a need to also focus on how GnRH neurons initiate and maintain their identity during prenatal and postnatal periods. This review will provide a brief overview of what is known about these processes and several gaps in our knowledge, with an emphasis on how disruption of GnRH neuronal identity can lead to CHH phenotypes.

Seminal plasma metabolomics signatures of normosmic congenital hypogonadotropic hypogonadism

BackgroundNormosmic congenital hypogonadotropic hypogonadism (nCHH) is a rare disease, whose pathogenesis remains unclear. Here, we conducted untargeted metabolomics and lipidomics to identify seminal plasma signatures of nCHH, and to study the effect of LH and FSH deficiency on semen. MethodsTwenty-five diagnosed patients with nCHH (HH group) and twenty-three healthy participants (HC group) were enrolled. Laboratory parameters, seminal plasma samples and patients’ medical data were collected. Untargeted metabolomics and lipidomic profiling were performed using mass spectrometry (MS). ResultsThe metabolomics profiling are altered among patients with nCHH and healthy controls. There are 160 kinds of differential metabolites and the main different lipid species are TAG, PC, SM and PE. ConclusionsThe metabolomics profiles in patients with nCHH changed. We hope that this work provides important insights into the pathophysiology of nCHH.

Defective jagged-1 signaling affects GnRH development and contributes to congenital hypogonadotropic hypogonadism.

In vertebrate species, fertility is controlled by gonadotropin-releasing hormone (GnRH) neurons. GnRH cells arise outside the central nervous system, in the developing olfactory pit, and migrate along olfactory/vomeronasal/terminal nerve axons into the forebrain during embryonic development. Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome are rare genetic disorders characterized by infertility, and they are associated with defects in GnRH neuron migration and/or altered GnRH secretion and signaling. Here, we documented the expression of the jagged-1/Notch signaling pathway in GnRH neurons and along the GnRH neuron migratory route both in zebrafish embryos and in human fetuses. Genetic knockdown of the zebrafish ortholog of JAG1 (jag1b) resulted in altered GnRH migration and olfactory axonal projections to the olfactory bulbs. Next-generation sequencing was performed in 467 CHH unrelated probands, leading to the identification of heterozygous rare variants in JAG1. Functional in vitro validation of JAG1 mutants revealed that 7 out of the 9 studied variants exhibited reduced protein levels and altered subcellular localization. Together our data provide compelling evidence that Jag1/Notch signaling plays a prominent role in the development of GnRH neurons, and we propose that JAG1 insufficiency may contribute to the pathogenesis of CHH in humans.

Autism-linked NLGN3 is a key regulator of gonadotropin-releasing hormone deficiency.

Gonadotropin-releasing hormone (GnRH) deficiency (GD) is a disorder characterized by absent or delayed puberty, with largely unknown genetic causes. The purpose of this study was to obtain and exploit gene expression profiles of GnRH neurons during development to unveil novel biological mechanisms and genetic determinants underlying GD. Here, we combined bioinformatic analyses of immortalized and primary embryonic GnRH neuron transcriptomes with exome sequencing from GD patients to identify candidate genes implicated in the pathogenesis of GD. Among differentially expressed and filtered transcripts, we found loss-of-function (LoF) variants of the autism-linked neuroligin 3 (NLGN3) gene in two unrelated patients co-presenting with GD and neurodevelopmental traits. We demonstrated that NLGN3 is upregulated in maturing GnRH neurons and that NLGN3 wild-type, but not mutant, protein promotes neuritogenesis when overexpressed in developing GnRH cells. Our data represent proof of principle that this complementary approach can identify new candidate GD genes and demonstrate that LoF NLGN3 variants can contribute to GD. This novel genotype-phenotype correlation implies common genetic mechanisms underlying neurodevelopmental disorders, such as GD and autistic spectrum disorder.

Mutation spectrum of Kallmann syndrome: identification of five novel mutations across ANOS1 and FGFR1

BackgroundKallmann syndrome (KS) is a common type of idiopathic hypogonadotropic hypogonadism. To date, more than 30 genes including ANOS1 and FGFR1 have been identified in different genetic models of KS without affirmatory genotype–phenotype correlation, and novel mutations have been found.MethodsA total of 35 unrelated patients with clinical features of disorder of sex development were recruited. Custom-panel sequencing or whole-exome sequencing was performed to detect the pathogenic mutations. Sanger sequencing was performed to verify single-nucleotide variants. Copy number variation-sequencing (CNV-seq) was performed to determine CNVs. The pathogenicity of the identified variant was predicted in silico. mRNA transcript analysis and minigene reporter assay were performed to test the effect of the mutation on splicing.ResultsANOS1 gene c.709 T > A and c.711 G > T were evaluated as pathogenic by several commonly used software, and c.1063-2 A > T was verified by transcriptional splicing assay. The c.1063-2 A > T mutation activated a cryptic splice acceptor site downstream of the original splice acceptor site and resulted in an aberrant splicing of the 24-basepair at the 5′ end of exon 8, yielding a new transcript with c.1063–1086 deletion. FRFR1 gene c.1835delA was assessed as pathogenic according to the ACMG guideline. The CNV of del(8)(p12p11.22)chr8:g.36140000_38460000del was judged as pathogenic according to the ACMG & ClinGen technical standards.ConclusionsHerein, we identified three novel ANOS1 mutations and two novel FGFR1 variations in Chinese KS families. In silico prediction and functional experiment evaluated the pathogenesis of ANOS1 mutations. FRFR1 c.1835delA mutation and del(8)(p12p11.22)chr8:g.36140000_38460000del were assessed as pathogenic variations. Therefore, our study expands the spectrum of mutations associated with KS and provides diagnostic evidence for patients who carry the same mutation in the future.

Puberty induction in boys with congenital isolated hypogonadotropic hypogonadism

Gonadotropin therapy in boys with congenital isolated hypogonadotropic hypogonadism helps to increase testes volume and induce spermatogenesis in comparison with testosterone therapy. However, difficulties with dose titration, partial therapy success, absence of generally accepted regimen protocols don't allow to use this therapy in order to induce puberty in adolescents with Kallmann syndrome or normosmic hypogonadotropic hypogonadism. To assess the effectiveness of combination hormonal replacement therapy via human chorionic gonadotropin and recombinant follicle stimulation hormone in adolescents with congenital isolated normosmic hypogonadotropic hypogonadism and with Kallmann syndromeMATERIALS AND METHODS: This is an open single-center prospective non-controlled study. Boys with hypogonadotropic hypogonadism were receiving hormonal replacement therapy for 12 months. Initial dose of human chorionic gonadotropin was 500 IU per week. Initial dose of recombinant follicle stimulation hormone was 37.5 IU per week. Doses were doubled in 6 months. Antropometric data, Tanner stage, testes volumes, inhibin B and anti-Mullerian hormone (AMH) levels were evaluated in all the patients before the treatment, after 6 and 12 months of the therapy. 8 boys with hypogonadotropic hypogonadism were included into the study. Median age before therapy initiation was 15.7 years [15.33; 16.41]. In 12 months after the therapy initiation puberty development, testosterone increase from 0.44 [0.34;0.62] to 4.39 [0.88;10.51] nmol/l (p=0.012), AMH decrease from 35.70 [18.00;59.00] to 14.41 [11.60;16.65] ng/ml were noted in all the patients (p=0.017). Testes volumes increase and inhibin B level increase were not statistically significant. Gonadotropin therapy is effective in order to puberty initiation in adolescents with congenital hypogonadotropic hypogonadism. In helps to achieve not only androgenization, but also to Sertoli cells maturation.

SIN3A Defects Associated with Syndromic Congenital Hypogonadotropic Hypogonadism: An Overlap with Witteveen-Kolk Syndrome

Introduction: Congenital hypogonadotropic hypogonadism (CHH) is a rare condition caused by GnRH deficiency. More than 40 genes have been associated with the pathogenesis of CHH, but most cases still remain without a molecular diagnosis. Mutations involving the same gene (e.g., FGFR1, PROK2/PROKR2, CHD7) were found to cause normosmic CHH and Kallmann syndrome (KS), with and without associated phenotypes, illustrating the coexistence of CHH with signs of other complex syndromes. The Witteveen-Kolk syndrome (WITKOS), caused by defects of the SIN3A gene, is a heterogeneous disorder characterized by distinctive facial features, microcephaly, short stature, delayed cognitive, and motor development. Although micropenis and cryptorchidism have been reported in this syndrome, WITKOS has not been formally associated with CHH so far. Patients and Methods: A man with KS associated with mild syndromic features (S1) and a boy with global developmental delay, syndromic short stature, micropenis and cryptorchidism (S2), in whom common genetic defects associated with CHH and short stature had been previously excluded, were studied by either chromosomal microarray analysis or whole exome sequencing. Results: Rare SIN3A pathogenic variants were identified in these 2 unrelated patients with CHH phenotypic features. A 550 kb deletion at 15q24.1, including the whole SIN3A gene, was identified in S1, and a SIN3A nonsense rare variant (p.Arg471*) was detected in S2. Conclusion: These findings lead us to propose a link between SIN3A defects and CHH, especially in syndromic cases, based on these 2 patients with overlapping phenotypes of WITKOS and CHH.